From this day our beloved son His Royal Highness Prince Guillaume will carry in his capacity as heir apparent to the Crown of the Grand Duchy of Luxembourg and the Grand Ducal Fidéicommis [Trust], the titles of Hereditary Grand Duke of Luxembourg, Hereditary Prince of Nassau, Prince of Bourbon-Parme.

The text of the Grand-Ducal decree was found at the website of the Government of Luxembourg. I have tried to locate the decree in the Legal Gazette (Memorial), but as far as I know it was not published there.